knock, hit, jut, blow, break, bulge, find, dislodge, encounter, protuberance, more...

indent, depression, dent

bruise, contusion, hematoma, swelling, lump, more...

small, little, big, slight, large, hard, nasty, bad, red, tiny, huge

small lump,   hit on the head,   pregnant belly,   small swelling,   raised surface,   small protuberance,   kick myself,   hit head,   hitting his head,   lump on the head